<script setup>
  import { ref, watch } from 'vue'
  import { useMouseInElement } from '@vueuse/core';


  // 图片列表
  defineProps({
    imageList: {
      type: Array,
      default: () => []
    }
  })

  //小图切换大图显示下标
  const activeIndex = ref(0)
  const enterHandle = (i) => {
    activeIndex.value = i
  }

  //获取鼠标相对大图位置
  const bigImg = ref(null)
  const { elementX, elementY, isOutside } = useMouseInElement(bigImg)

  //控制滑块跟随鼠标移动（监听elementX/Y,一旦变化则重新设置top和left）
  const left = ref(0)
  const top = ref(0)
  const positionX = ref(0)
  const positionY = ref(0)
  watch([elementX, elementY, isOutside], () => {

    //如果鼠标没有进入到大图则以下的不执行
    if (isOutside.value) return
    //有效范围内的滑块位置  横向和纵向
    if (elementX.value > 100 && elementX.value < 300) {
      left.value = elementX.value - 100
    }
    if (elementY.value > 100 && elementY.value < 300) {
      top.value = elementY.value - 100
    }
    //边界值的滑块位置
    if (elementX.value >= 300) { left.value = 200 }
    if (elementX.value <= 100) { left.value = 0 }
    if (elementY.value >= 300) { top.value = 200 }
    if (elementY.value <= 100) { top.value = 0 }
    //控制放大镜的显示
    positionX.value = -left.value * 2
    positionY.value = -top.value * 2
  })
</script>


<template>
  <div class="goods-image">

    <!-- 左侧大图-->
    <div class="middle" ref="bigImg">
      <img :src="imageList[activeIndex]" alt="" />
      <!-- 蒙层小滑块 -->
      <div v-show="!isOutside" class="layer" :style="{ left: `${left}px`, top: `${top}px` }"></div>
    </div>
    <!-- 小图列表 -->
    <ul class="small">
      <li v-for="(img, i) in imageList" :key="i" @mouseenter="enterHandle(i)" :class="{ active: i === activeIndex }">
        <img :src="img" alt="" />
      </li>
    </ul>
    <!-- 放大镜大图 -->
    <div class="large" :style="[
      {
        backgroundImage: `url(${imageList[activeIndex]})`,
        backgroundPositionX: `${positionX}px`,
        backgroundPositionY: `${positionY}px`,
      },
    ]" v-show="!isOutside"></div>
  </div>
</template>

<style
  scoped
  lang="scss"
>
  .goods-image {
    width: 480px;
    height: 400px;
    position: relative;
    display: flex;

    .middle {
      width: 400px;
      height: 400px;
      background: #f5f5f5;
    }

    .large {
      position: absolute;
      top: 0;
      left: 412px;
      width: 400px;
      height: 400px;
      z-index: 500;
      box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
      background-repeat: no-repeat;
      // 背景图:盒子的大小 = 2:1  将来控制背景图的移动来实现放大的效果查看 background-position
      background-size: 800px 800px;
      background-color: #f8f8f8;
    }

    .layer {
      width: 200px;
      height: 200px;
      background: rgba(0, 0, 0, 0.2);
      // 绝对定位 然后跟随咱们鼠标控制left和top属性就可以让滑块移动起来
      left: 0;
      top: 0;
      position: absolute;
    }

    .small {
      width: 80px;

      li {
        width: 68px;
        height: 68px;
        margin-left: 12px;
        margin-bottom: 15px;
        cursor: pointer;

        &:hover,
        &.active {
          border: 2px solid $xtxColor;
        }
      }
    }
  }
</style>